A pleasure at the beach? You may not have it up the creek (6)
I believe the answer is:
paddle
I believe this is a double definition.
'a pleasure at the beach?' is the first definition.
'you may not have it up the creek' is the second definition.
(ref to the phrase 'up the creek without a paddle')
(Other definitions for paddle that I've seen before include "If you were up the creek without one you'd be in trouble!" , "Walk with bare feet in shallow water" , "Blade to propel" , "Blade of a water wheel" , "dabble in the water" .)