One of the top people in the building trade alters construction (6)
I believe the answer is:
slater
'one of the top people in the building trade' is the definition.
I can't tell whether this definition defines the answer.
'alters construction' is the wordplay.
'construction' indicates an anagram (answer constructed from certain letters).
'alters' anagrammed gives 'SLATER'.
Can you help me to learn more?
(Other definitions for slater that I've seen before include "Alerts (anag) - building worker" , "High-up person" , "Roof-worker" , "Craftsman" , "Layer of roof slabs" .)