Maybe the sapper is out of breath! (7)
I believe the answer is:
perhaps
'maybe' is the definition.
(synonyms)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for perhaps that I've seen before include "say" , "Possibly but not certainly" , "Not necessarily" , "It may be" , "Conceivably" .)