It makes it hard to go in court to describe barren years' sex lives (8)

'it makes it hard to go' is the definition.
(condition causing pain when urinating)

'court to describe barren years' sex lives' is the wordplay.
'court' becomes 'ct'.
'to describe' means one lot of letters goes inside another.
'barren' suggests removing the centre (the word is emptied out or made barren).
'sex' becomes 'it' (a common euphemism).
'lives' becomes 'is' ('be' can be a synonym of 'live').
'years' with its centre removed is 'ys'.
'ct' enclosing 'ys' is 'cyst'.
'cyst'+'it'+'is'='CYSTITIS'

'in' acts as a link.