Anchor angler at sea holds quietly (7)
I believe the answer is:
grapnel
'anchor' is the definition.
(I've seen this before)
'angler at sea holds quietly' is the wordplay.
'at sea' indicates an anagram.
'holds' indicates putting letters inside.
'quietly' becomes 'p' (p for piano and quiet).
'angler' is an anagram of 'granel'.
'granel' going around 'p' is 'GRAPNEL'.
(Other definitions for grapnel that I've seen before include "Rope/hook device" , "Grappling hook" , "Hook on rope" , "Tool with hooks for grasping and holding" , "Grasping implement" .)