It's an absurd pretence for Henry joining up with Dara in Clare (7)
I believe the answer is:
charade
'it's an absurd pretence' is the definition.
(a ridiculous pretence or show)
'henry joining up with dara in clare' is the wordplay.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'joining' says to put letters next to each other.
'up with' says the letters should be written backwards (move letters in down clue up).
'in' means one lot of letters goes inside another.
'clare' becomes 'ce' (I've seen this in other clues).
'dara' in reverse letter order is 'arad'.
'h'+'arad'='harad'
'harad' placed inside 'ce' is 'CHARADE'.
'for' acts as a link.
(Other definitions for charade that I've seen before include "Word-guessing riddle" , "Party game using mime" , "Pretence - travesty" , "Pretence; parlour game" , "Travesty, mockery" .)