Fuse in centre containing high explosive (6)
I believe the answer is:
cohere
'fuse' is the definition.
(thesaurus)
'centre containing high explosive' is the wordplay.
'centre' becomes 'core' (core is a kind of centre).
'containing' means one lot of letters goes inside another.
'high explosive' becomes 'he'.
'core' placed around 'he' is 'COHERE'.
'in' is the link.
(Other definitions for cohere that I've seen before include "Form a whole" , "Stick firmly together" , "Hang together" , "Stick or hold together and resist separation" , "Hold firmly together" .)