Limb turned to solid jelly (3)
I believe the answer is:
gel
'solid jelly' is the definition.
'gel' can be an answer for 'jelly' (thesaurus). I am not certain of the 'solid' bit.
'limb turned' is the wordplay.
'limb' becomes 'leg' (leg is a kind of limb).
'turned' shows that the letters should be reversed in order.
'leg' in reverse letter order is 'GEL'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for gel that I've seen before include "Set, become firmer" , "Become jelly-like" , "Posh female" , "well-spoken deb?" , "Work well together" .)