Desire to eat a snake and be irritable? (7)
I believe the answer is:
waspish
'be irritable?' is the definition.
(I've seen this before)
'desire to eat a snake' is the wordplay.
'desire' becomes 'wish' (wish is a kind of desire).
'to eat' means one lot of letters goes inside another.
'a snake' becomes 'asp' (asp is a kind of snake).
'wish' enclosing 'asp' is 'WASPISH'.
'and' acts as a link.
(Other definitions for waspish that I've seen before include "Petulant" , "Easily angered - with black and yellow stripes?" , "Bad-tempered like striped insect" , "Easily-provoked" , "ill-tempered" .)