Tight and loose (4)
I believe the answer is:
fast
This clue is a double definition.
'tight' is the first definition.
(both can mean secure)
'loose' is the second definition.
(thesaurus)
'and' acts as a link.
(Other definitions for fast that I've seen before include "Abstain from eating" , "Moored - fleet" , "eg Ramadan; speedy" , "Flying" , "Abstain from food/drink" .)