Slender winches used now and then, won't hold much weight (4,3)

'winches used now and then won't hold much weight' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'slender' is the wordplay.
I cannot quite understand how this works, but
'slender' could be 'thin' (synonyms) and 'thin' is located in the answer.
The remaining letters 'ice' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?