Is the restraint in that spot? (7)
I believe the answer is:
therein
'in that spot?' is the definition.
Both the answer and definition are adverbs. Perhaps you can see a link between them that I can't see?
'is the restraint' is the wordplay.
'restraint' becomes 'rein' (I've seen this before).
'the'+'rein'='THEREIN'
Can you help me to learn more?
(Other definitions for therein that I've seen before include "Inside that" , "in that respect" , "enclosed by that place?" , "Neither (anag) - into that" .)