Country - it's in Mastermind, perhaps (5,7)
I believe the answer is:
great britain
'country' is the definition.
(Great Britain is an example)
'it's in mastermind perhaps' is the wordplay.
I cannot really see how this works, but
'in' is within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for great britain that I've seen before include "North European country" , "GB in full" , "Part of the UK" , "Bulldog can stand for this" , ""Country" of England, Scotland and Wales" .)