The heartless help out with single bell (9)
I believe the answer is:
telephone
'bell' is the definition.
(telephone bell is a kind of bell)
'the heartless help out with single' is the wordplay.
'heartless' means to remove the middle letters.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'with' says to put letters next to each other.
'single' becomes 'one' (a single thing - only one).
'the' with its middle taken out is 'te'.
'help' is an anagram of 'leph'.
'te'+'leph'+'one'='TELEPHONE'
(Other definitions for telephone that I've seen before include "Call, ring" , "It transmits speech at a distance" , "Reference book for callers" , "Transmitter of spoken words" , "Communications device" .)