The most recent to lose heart at last? (6)
I believe the answer is:
latest
'the most recent' is the definition.
(thesaurus)
'to lose heart at last?' is the wordplay.
'to' becomes 'shut' (I've seen this before).
'lose heart' suggests removing the centre (I've seen 'losing heart' mean this).
'at' says to put letters next to each other (I've seen this in other clues).
'last?' becomes 'late' ('late' can be similar in meaning to 'last'**).
'shut' with its centre taken out is 'st'.
'st' put after 'late' is 'LATEST'.
(Other definitions for latest that I've seen before include "Most recent or most unpunctual" , "Most recent (news)" , "News update" , "hot bit of news" , "most behind time" .)