Recess would be pleasant about the end of March (5)
I believe the answer is:
niche
'recess' is the definition.
(I know that recess can be written as niche)
'pleasant about the end of march' is the wordplay.
'pleasant' becomes 'nice' (associated in meaning).
'about' means one lot of letters goes inside another.
'the end of' suggests the final letters.
The final letter of 'march' is 'h'.
'nice' placed around 'h' is 'NICHE'.
'would be' acts as a link.
(Other definitions for niche that I've seen before include "somewhere comfortable" , "Place that's cosy" , "Small recess or cranny" , "Speciality" , "A small recess or easy job" .)