It's hard to get on when relative catches cold (8)
I believe the answer is:
unicycle
'it's hard to get on' is the definition.
I can't judge whether this defines the answer.
'relative catches cold' is the wordplay.
'relative' becomes 'uncle' (uncle is a kind of relative).
'catches' indicates putting letters inside.
'cold' becomes 'icy' (similar in meaning).
'uncle' placed around 'icy' is 'UNICYCLE'.
'when' acts as a link.
Can you help me to learn more?
(Other definitions for unicycle that I've seen before include "that requires someone well-balanced in control" , "Means of transport" , "One-wheeler" , "One-wheeled transport" , "One saddled" .)