Get snappy here when very warm in rear of ship (5,2)
I believe the answer is:
photo op
'get snappy here' is the definition.
(snap can mean a photograph)
'very warm in rear of ship' is the wordplay.
'very warm' becomes 'hot' (I've seen this before).
'in' indicates putting letters inside.
'rear of ship' becomes 'poop' (as in the poop deck on a ship).
'hot' going into 'poop' is 'PHOTO-OP'.
'when' acts as a link.
(Other definitions for photo op that I've seen before include "Chance to shoot" , "Chance for publicity" .)