Other than the end rhyme, what is common to the words "lock" and "shock"?
Both can refer to hair - a lock is a ringlet of hair, shock is a bushy mass of hair.
Some clues that use this meaning of the words:
Guardian 24958 (Rufus): Emphasise need for second lock (6) STRESS
S (second) TRESS (lock)
Times 24888: Locks securing books, nothing worth listening to (3,3)
Guardian 25098 (Puck): Soldiers entertained by Spice Girl? Ring doctor — one may go into shock (5,4) M____ _O__
FT 13161 (Alberich): Ostentation and fuss associated with primitive form of shock treatment (9) _O______R
Guardian 24369 (Pasquale): Sort of time when one may have an awful shock? (3,4,3)
FT 13683 (Jason): Attendant with the very best lock (8)
Independent 7023 (Monk): They're designed to cause shock waves (8) _R_M____