Repairman reassembled china with first half of cement (8)
I believe the answer is:
mechanic
'repairman' is the definition.
(mechanic is a kind of repairman)
'reassembled china with first half of cement' is the wordplay.
'reassembled' indicates an anagram.
'with' is a charade indicator (letters next to each other).
'first half of' suggests halving the letters.
'cement' cut in half is 'cem'.
'china' put after 'cem' is 'cemchina'.
'cemchina' with letters rearranged gives 'MECHANIC'.
(Other definitions for mechanic that I've seen before include "Trained garage assistant" , "Person who repairs cars etc." , "Skilled worker on machines" , "One employed by F1 team" , "Expert in fixing cars and machinery" .)