Each part of a clever yarn (5)
I believe the answer is:
every
'each' is the definition.
(synonyms)
'part of a clever yarn' is the wordplay.
'part of' says the answer is hidden in the clue.
'EVERY' can be found hidden inside 'clever yarn'.
(Other definitions for every that I've seen before include "'God bless us - - one !'" , "Each one without exception" , "Each of a number" , "Each (one of a set)" , "Each single (item)" .)