Ground troops? (11,4)
I believe the answer is:
territorial army
'ground troops?' is the definition.
The answer and definition can be both groups as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'troops?' is the wordplay.
I cannot really understand how this works, but
'troops?' could be 'army' (I've seen this in another clue) and 'army' is present in the answer.
The remaining letters 'territorial' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for territorial army that I've seen before include "volunteers" , "Soldiers" .)