Head lost in despair abandoned hope (6)
I believe the answer is:
aspire
'hope' is the definition.
(I've seen this in another clue)
'head lost in despair abandoned' is the wordplay.
'head lost in' means to remove the first letter.
'abandoned' is an anagram indicator (the original order is abandoned).
'despair' with its first letter taken off is 'espair'.
'espair' anagrammed gives 'ASPIRE'.
(Other definitions for aspire that I've seen before include "Yearn, dream (towards)" , "Aim (for higher things)" , "Long" , "Have hopes (to achieve something)" , "Is a rep (anag.)" .)