Positional indicators are used to get words or parts of words into the order they are seen in the answer word. The indicators used will suggest a word needs to be put somewhere other than it appears in the clue's surface or that it goes with another word.
NOTE: The type of word used to indicate position will be different dependent on whether the clue is an across or a down. This is because across clues are on the horizontal and down clues are on the vertical. Further explanation of this will follow the examples.
Let's take a look at positional indicators in action:
To get the words BOY and COW to make the word COWBOY the setter needs to make BOY go after COW. To do this she will employ a positional indicator.
For an across clue:
BOY chasing COW ...
BOY after COW ...
BOY on COW ... (on - as a positional indicator - always means after in an across clue)
For a down clue:
BOY supporting COW ...
BOY under COW ...
BOY submerged by COW ...
NOTE: Can you see how the down clue positional indicators give a sense of one bit of fodder being under or holding up the other? This is because down clues are positioned vertically in the grid - these indicators are down clue specific and would not be suitable for an across clue. However, indicators such as AFTER/FOLLOWING or any others that do not have a specific association to the vertical may be used in either down or across clues.
Any word that fairly indicates that one piece of fodder goes after, before, under, over or with another may be used as a positional indicator. Here are some more examples.
Across positional indicators: FOLLOWING/WITH/BY
Down positional indicators: BENEATH/HOLDING UP
A positional indicator used in a DOWN clue:
Punish bishop on ecstasy in county court (7)
punish - CORRECT (definition)
bishop - RR (abbreviation for right reverend)
on - positional indicator
ecstasy - E (abbreviation for the drug ecstasy)
in - insertion indicator
county - CO (abbreviation for county)
court - CT (abbreviation for court)
Notice that if we write the answer word as it would appear in a vertical grid positioning ...
... we can see that the wordplay element RR does indeed go ON the wordplay element E.
And in an ACROSS clue:
Live comfortably on dole at first (5)
live - DWELL (definition)
comfortably - WELL (living comfortably/well)
on - positional indicator
dole - first letter fodder
at first - first letter indicator (indicating the first letter of dole)
Remember that in an across clue ON means AFTER. The clue identifies WELL and D, but to get those pieces of fodder into the correct order to form the answer word the positional indicator ON is employed.