What may make models flipping love haircare product (4)
I believe the answer is:
lego
'what may make models' is the definition.
(as in Lego bricks)
'flipping love haircare product' is the wordplay.
'flipping' is a reversal indicator.
'love' becomes 'o' (love means zero in tennis).
'haircare product' becomes 'gel' (hair gel).
'o'+'gel'='ogel'
'ogel' in reverse letter order is 'LEGO'.
(Other definitions for lego that I've seen before include "Toy consisting of interlocking plastic bricks" , "Toy with interlocking blocks" , "Toy construction set" , "construction kit" , "Children's building bricks" .)