The way to speak – if you want to sound tongue-tied! (7)
I believe the answer is:
Here is my best explanation:
'you want to sound tongue-tied' is the definition.
I can't tell whether this definition defines the answer.
'the way to speak' is the subsidiary indication.
'the way' becomes 'st'.
'to' says to put letters next to each other.
'speak' becomes 'utter' ('utter' can be a synonym of 'speak'**).
'if' is the link.
(Other definitions for stutter that I've seen before include "Speech impediment", "Stumble over words", "Hesitation in speech over first consonants", "s...say?", "Speech defect in repeating first consonants of words", "Speak haltingly", "Struggle to speak", "Falter", "Stammer" and "Struggle with one's words".)