Becomes strained when speaking a few words (6)
I believe the answer is:
phrase
'a few words' is the definition.
'becomes strained when speaking' is the wordplay.
'becomes strained' becomes 'frays'.
'when speaking' shows a homophone (sound like).
'frays' sounds like 'PHRASE'.
(Other definitions for phrase that I've seen before include "Sequence of words" , "Saying" , "Group of words within a sentence" , "Word (in a particular way)" , "Set of words for sherpa" .)