For him to laze is unusual (6)
I believe the answer is:
zealot
'for him' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'to laze is unusual' is the wordplay.
'is unusual' indicates anagramming the letters.
'to'+'laze'='tolaze'
'tolaze' with letters rearranged gives 'ZEALOT'.
Can you help me to learn more?
(Other definitions for zealot that I've seen before include "A fanatic or extremist" , "Fervent, perhaps militant, proponent" , "Fervent enthusiast" , "Fervent, even militant, proponent of something" , "A fanatic, driven person" .)