The start of the holidays in pleasant recess (5)
I believe the answer is:
niche
'recess' is the definition.
(I know that recess can be written as niche)
'the start of the holidays in pleasant' is the wordplay.
'the start of' indicates taking the first letters.
'in' is an insertion indicator.
'pleasant' becomes 'nice' (associated in meaning).
The first letter of 'holidays' is 'h'.
'h' inserted within 'nice' is 'NICHE'.
(Other definitions for niche that I've seen before include "Suitable position (in market, life etc)" , "ideal position" , "Select place in market" , "Suitable position or small alcove" , "Calling" .)