Stick of explosive hidden in central part (6)
I believe the answer is:
cohere
'stick' is the definition.
('cohere' can be a synonym of 'stick')
'of explosive hidden in central part' is the wordplay.
'of' becomes 'o'.
'explosive' becomes 'he' (abbreviation for high explosive).
'hidden in' is an insertion indicator.
'central' becomes 'c' (common abbreviation in various government acronyms).
'part' becomes 're' (re is a kind of part**).
'o'+'he'='ohe'
'c'+'re'='cre'
'ohe' going inside 'cre' is 'COHERE'.
(Other definitions for cohere that I've seen before include "Hang together" , "Hold firmly together" , "Stick together, remain united" , "Even; without jerks" , "Stick firmly together" .)