Inflammation of the ear? Go back in; sit it before outstart (6)
I believe the answer is:
otitis
'inflammation of the ear?' is the definition.
(I've seen this before)
'back in sit it before outstart' is the wordplay.
'back' is a reversal indicator.
'in' means one lot of letters goes inside another.
'before' means one lot of letters go next to another.
'outstart' becomes 'o' (start of the word 'out').
'sit' enclosing 'it' is 'sitit'.
'sitit'+'o'='sitito'
'sitito' back-to-front is 'OTITIS'.
'go' is the link.
(Other definitions for otitis that I've seen before include "Inflammation of the ear" , "Ear disease" , "trouble with hearing device" , "pain" , "problem for listener" .)