Young swimmers stirred old paste (8)
I believe the answer is:
tadpoles
'young swimmers' is the definition.
'tadpoles' can be an answer for 'swimmers' (I have seen 'Little swimmers' mean 'tadpoles' so perhaps 'swimmers' could also mean 'tadpoles'). I'm not certain of the 'young' bit.
'stirred old paste' is the wordplay.
'stirred' indicates an anagram.
'old'+'paste'='oldpaste'
'oldpaste' with letters rearranged gives 'TADPOLES'.
Can you help me to learn more?
(Other definitions for tadpoles that I've seen before include "Immature frogs" , "Larvae of frogs or toads" , "Larval frogs" , "Stop deal (anag.)" , "Little swimmers" .)