Forest guides keep rook within limits (7)
I believe the answer is:
rangers
'forest guides' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe they are linked in a way I don't understand?
'keep rook within limits' is the wordplay.
'keep rook' becomes 'r' (I can't explain this - if you can you should give a lot more credence to this answer).
'within' is an insertion indicator.
'limits' becomes 'ranges' (range is a kind of limit).
'r' inserted within 'ranges' is 'RANGERS'.
Can you help me to learn more?
(Other definitions for rangers that I've seen before include "Park officials - Glasgow FC" , "football team" , "Park or forest keepers" , "Administrators of Forest" , "Forest staff" .)