Checks case for source of smelly underwear (5)
I believe the answer is:
vests
'checks case for source of smelly underwear' is the definition.
I can't tell whether this defines the answer.
'checks case for source of smelly' is the wordplay.
'checks' becomes 'vets' (I've seen this before).
'case for' indicates putting letters inside.
'source of' says to take the initial letters.
The initial letter of 'smelly' is 's'.
'vets' placed around 's' is 'VESTS'.
Can you help me to learn more?
(Another definition for vests that I've seen is " Sleeveless garments".)