Nick spells strings of words? (9)
I believe the answer is:
sentences
This clue is a double definition.
'nick spells' is the first definition.
(spells in prison or 'the nick')
'strings of words?' is the second definition.
(Other definitions for sentences that I've seen before include "Groups of words as punishments for crimes" , "Judicial penalties" , "Judicial punishments or words arrangements" , "Word sets of senescent origin" , "Words with grammatical structures" .)