Space to sing meant heartless delight (11)
I believe the answer is:
enchantment
'delight' is the definition.
(I've seen this before)
'space to sing meant heartless' is the wordplay.
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'to sing' becomes 'chant' (chanting is a kind of singing).
'heartless' suggests removing the centre.
'meant' with its centre taken out is 'ment'.
'en'+'chant'+'ment'='ENCHANTMENT'
(Other definitions for enchantment that I've seen before include "Spell -- delight" , "more powerful the further away?" , "Charm, spell" , "Charm, delight" , "Charm, allure" .)