Catch sight of mate returning with computers (7)
I believe the answer is:
laptops
'computers' is the definition.
(laptop is a kind of computer)
'catch sight of mate returning' is the wordplay.
'catch sight of' becomes 'spot' (to spot is to notice or catch sight of).
'mate' becomes 'pal' (I've seen this before).
'returning' is a reversal indicator.
'spot'+'pal'='spotpal'
'spotpal' in reverse letter order is 'LAPTOPS'.
'with' is the link.
(Other definitions for laptops that I've seen before include "Portable computers" , "more than one PC" , "PCs" .)