Cat and ram loose on runway (6)
I believe the answer is:
tarmac
'runway' is the definition.
(I've seen this before)
'cat and ram loose' is the wordplay.
'and' is a charade indicator (letters next to each other).
'loose' indicates anagramming the letters (letters are loosened from their original positions).
'cat' put after 'ram' is 'ramcat'.
'ramcat' anagrammed gives 'TARMAC'.
'on' acts as a link.
(Other definitions for tarmac that I've seen before include "Trade name for road surfacing material" , "black one" , "Airport runway(s)" , "Road paving material" , "Road-surfacing material" .)