Instinctive, small worry: chap’s out of breath a lot? (4-2-3-5)
I believe the answer is:
seat-of-the-pants
'instinctive' is the definition.
(seat of the pants means done instinctively)
'small worry chap's out of breath a lot?' is the wordplay.
I cannot really see how this works, but
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is present in the answer.
'worry' could be 'eat' (something worrying may eat someone up) and 'eat' is found in the answer.
'of' could be 'o' and 'o' is located in the answer.
'a' could be 'an' and 'an' is found in the answer.
'chap' could be 'he' and 'he' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for seat-of-the-pants that I've seen is " Instinctive".)