Tanned 2 in need of a wash (8)
I believe the answer is:
unbathed
'tanned 2' is the definition.
The definition suggests an adjective which matches the answer.
'in need of a wash' is the wordplay.
'in' is an insertion indicator.
'need of' becomes 'und' (I can't justify this - if you can you should believe this answer much more).
'a wash' becomes 'bathe' (I've seen this before).
'und' placed around 'bathe' is 'UNBATHED'.
Can you help me to learn more?
(Another definition for unbathed that I've seen is " smelly?".)