Decorated nail of first two digits, curiously (6)
I believe the answer is:
inlaid
'decorated' is the definition.
(similar in meaning)
'nail of first two digits curiously' is the wordplay.
'two digits' can mean two substitutions for 'digit'.
'of first' suggests taking the first letters (I've seen 'first' mean this).
'digit' becomes 'I' (I is an example).
'curiously' indicates anagramming the letters.
The initial letter of 'digit' is 'd'.
'nail'+'d'+'i'='naildi'
'naildi' with letters rearranged gives 'INLAID'.
(Other definitions for inlaid that I've seen before include "(Of decorative items) embedded" , "Chased" , "Having been set into surface to be parallel with it" , "Set into surface ornamentally" , "decorated with studs perhaps" .)