Carry across final slice of ginger cake (5)
I believe the answer is:
torte
'ginger cake' is the definition.
'torte' can be an answer for 'cake' (torte is a kind of cake). I'm not certain of the 'ginger' bit.
'carry across final slice' is the wordplay.
'carry' becomes 'tote' (toting is a kind of carrying).
'across' means one lot of letters goes inside another.
'final slice' becomes 'r' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tote' placed around 'r' is 'TORTE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for torte that I've seen before include "German cream cake" , "Sweet cake or tart" , "Rich sweet cake" , "1d [PASTRY]" , "Sweet cake (from Ger.)" .)