Decking put Royal Navy crew in a spot (9)
I believe the answer is:
adornment
'decking' is the definition.
(I've seen this before)
'royal navy crew in a spot' is the wordplay.
'royal navy' becomes 'RN' (abbreviation for Royal Navy).
'crew' becomes 'men' (I've seen this before).
'in' indicates putting letters inside.
'spot' becomes 'dot' (I've seen this before).
'rn'+'men'='rnmen'
'a'+'dot'='adot'
'rnmen' going within 'adot' is 'ADORNMENT'.
'put' is the link.
(Other definitions for adornment that I've seen before include "Embellishment" , "Making elaborate" , "Ornamentation" , "decking" , "decorating" .)