Tree by the beach still sheltering old policeman (4,4)

'tree' is the definition.
(coco palm is a kind of tree)

'still sheltering old policeman' is the wordplay.
'still' becomes 'calm' (similar in meaning).
'sheltering' indicates putting letters inside.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'policeman' becomes 'cop' (slang term).
'o'+'cop'='ocop'
'calm' placed around 'ocop' is 'COCO-PALM'.

'by the beach' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?