Overwhelmed by the chasm in dire need (8)
I believe the answer is:
engulfed
'overwhelmed' is the definition.
('engulfed' can be a synonym of 'overwhelmed')
'the chasm in dire need' is the wordplay.
'the chasm' becomes 'gulf' (gulf is a kind of chasm).
'in' is an insertion indicator.
'dire' indicates an anagram.
'need' is an anagram of 'ened'.
'gulf' put inside 'ened' is 'ENGULFED'.
'by' acts as a link.
(Other definitions for engulfed that I've seen before include "Swallowed up or overwhelmed" , "Possibly, stuck in a swamp" , "Swallowed up as by wave" , "Swallowed by as by waves" .)