Cross dresser initially put on jumper (4)
I believe the answer is:
rood
'cross' is the definition.
(rood is a kind of cross)
'dresser initially put on jumper' is the wordplay.
'initially' indicates taking the first letters.
'put on' says to put letters next to each other.
'jumper' becomes 'roo' (I've seen this before).
The initial letter of 'dresser' is 'd'.
'd' after 'roo' is 'ROOD'.
(Other definitions for rood that I've seen before include "Pole, perch or crucifix" , "The Holy . . . . was the Cross of Christ" , "Cross, crucifix" , "Old land measure of quarter of an acre" , "Old land measure and large cross in a church" .)