The son wants to get on but won't work hard (6)
I believe the answer is:
slacks
'get on but won't work hard' is the definition.
I can't tell whether this definition defines the answer.
'the son wants' is the wordplay.
'the son' becomes 's' (genealogical abbreviation for son).
'wants' becomes 'lacks' ('lack' can be a synonym of 'want').
's'+'lacks'='SLACKS'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for slacks that I've seen before include "bags" , "takes it easy" , "casual attire" , "Works lazily; trousers" , "Pants for casual wear" .)