Occasional short insect breaks inside camping shelter (12)
I believe the answer is:
intermittent
'occasional' is the definition.
(I've seen this before)
'short insect breaks inside camping shelter' is the wordplay.
'short' means to remove the last letter.
'insect' becomes 'termite' (termite is a kind of insect).
'breaks' means one lot of letters goes inside another.
'inside' becomes 'in' (**).
'camping shelter' becomes 'tent' (I've seen this before).
'termite' with its last letter taken off is 'termit'.
'in'+'tent'='intent'
'termit' put within 'intent' is 'INTERMITTENT'.
(Other definitions for intermittent that I've seen before include "Irregular" , "Occasional" , "On-and-off" , "Occurring irregularly" , "Occurring at intervals" .)