With “It’s a deal!” getting on again inside (6)
I believe the answer is:
agreed
'with it's a deal' is the definition.
I can't tell whether this defines the answer.
'getting on again inside' is the wordplay.
'getting on' becomes 'aged' (I've seen this before).
'again' becomes 're'.
'inside' is an insertion indicator.
'aged' going around 're' is 'AGREED'.
Can you help me to learn more?
(Other definitions for agreed that I've seen before include "Concurred - tallied" , "Accorded" , "Expressed willingness" , "matched" , "Of one mind" .)