Old man initially in touch is over the top (3,4)
I believe the answer is:
too much
'over the top' is the definition.
'old man initially in touch' is the wordplay.
'initially' suggests taking the first letters.
'in' means one lot of letters goes inside another.
The initial letters of 'old man' is 'om'.
'om' going within 'touch' is 'TOO MUCH'.
'is' is the link.
(Other definitions for too much that I've seen before include "More than enough" , "Existing in excessive quantity" , "More than is tolerable" , "More than is reasonable" , "Excess, more than is needed" .)