...wisp of red lint (7)
I believe the answer is:
tendril
'wisp' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'of red lint' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'red'+'lint'='redlint'
'redlint' anagrammed gives 'TENDRIL'.
Can you help me to learn more?
(Other definitions for tendril that I've seen before include "Twining shoot" , "Slender thread-like appendage of a plant" , "Slender curl or plant climber" , "Part of twining plant" , "A creeper, or a curl of hair" .)