Extremely bulky electrical connection that's back-to-front in memory (2,5)
I believe the answer is:
by heart
'in memory' is the definition.
(I've seen this in another clue)
'extremely bulky electrical connection that's back-to-front' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'electrical connection' becomes 'hear' (I can't justify this - if you can you should give a lot more credence to this answer).
'that's back to' suggests the final letters.
'bulky' with its centre removed is 'by'.
The final letter of 'front' is 't'.
'by'+'hear'+'t'='BY HEART'
Can you help me to learn more?
(Other definitions for by heart that I've seen before include "(Learnt) in memory" , "One way to remember" , "To know - - is to have in the memory" , "Parrot-fashion" , "Committed to memory" .)