Being hairy thanks to natural mutation? (9)
I believe the answer is:
tarantula
'being hairy' is the definition.
(I've seen this before)
'thanks to natural mutation?' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'to' means one lot of letters go next to another.
'mutation?' indicates an anagram (I've seen 'mutation' mean this).
'natural' is an anagram of 'rantula'.
'ta'+'rantula'='TARANTULA'
(Other definitions for tarantula that I've seen before include "Creepy-crawly" , "A large hairy tropical spider" , "hairy creature" , "small, venomous creature" , "Large venomous spider" .)