Critical party chasing gutless leader (5)
I believe the answer is:
grave
'critical' is the definition.
(similar in meaning)
'party chasing gutless leader' is the wordplay.
'party' becomes 'rave' (type of dance party).
'chasing' means one lot of letters go next to another (some letters chase after others).
'leader' indicates taking the first letters.
The first letter of 'gutless' is 'g'.
'rave' put after 'g' is 'GRAVE'.
(Other definitions for grave that I've seen before include "Burial place is serious" , "Solemn; tomb" , "Burial site" , "Dignified" , "In which to lay a corpse" .)