Bit of income sailor collects, a half-crown? (5)
I believe the answer is:
tiara
'half-crown?' is the definition.
(I've seen this before)
'bit of income sailor collects a' is the wordplay.
'bit of' says to take the initial letters.
'sailor' becomes 'tar' (tar is a kind of sailor**).
'collects' means one lot of letters goes inside another.
The initial letter of 'income' is 'i'.
'i' inserted inside 'tar' is 'tiar'.
'tiar'+'a'='TIARA'
(Other definitions for tiara that I've seen before include "Jewelled crescent-shaped headdress" , "Pope's triple-tiered crown" , "Women's head ornament" , "Jewelled head wear" , "Woman's headdress for very formal occasions" .)