Mean thing to have you, daughter and Irish boy keeping tryst regularly (5,5)

'mean thing to have you' is the definition.
(mean or nasty trick)

'daughter and irish boy keeping tryst regularly' is the wordplay.
I cannot really see how this works, but
'daughter' could be 'd' (genealogical abbreviation) and 'd' is found within the answer.
'irish' could be 'ir' (abbreviation) and 'ir' is present in the answer.
'boy' could be 'rick' and 'rick' is located in the answer.
This explanation may well be incorrect...