Mislay the ring in it that's too big (5)
I believe the answer is:
loose
'too big' is the definition.
I can't judge whether this defines the answer.
'mislay the ring in it' is the wordplay.
'mislay' becomes 'lose' (synonyms).
'the ring' becomes 'o' (letter resembling a ring).
'in it' is an insertion indicator.
'lose' going around 'o' is 'LOOSE'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for loose that I've seen before include "Lax or at large" , "Untie; dissolute" , "Unfixed" , "Promiscuous" , "wobbly" .)