Marry fool in duke, ignoring odd bits (5)
I believe the answer is:
unite
'marry fool' is the definition.
'unite' can be an answer for 'marry' (I've seen this before). I am not certain of the 'fool' bit.
'in duke ignoring odd bits' is the wordplay.
'in' means one lot of letters goes inside another.
'ignoring odd' indicates alternate letters (I've seen 'ignoring odds' mean this (the odd-numbered letters are removed)).
'bits' becomes 'nit' (I can't justify this - if you can you should believe this answer much more).
The alternate letters of 'duke' are 'ue'.
'ue' going around 'nit' is 'UNITE'.
Can you help me to learn more?
(Other definitions for unite that I've seen before include "Put together" , "Amalgamate" , "Come, or join together" , "Connect" , "pool resources" .)