Clever Texan holding summit? (6)
I believe the answer is:
vertex
'summit?' is the definition.
(thesaurus)
'clever texan holding' is the wordplay.
'holding' says the answer is hidden in the clue.
'VERTEX' is hidden in the letters of 'clever texan'.
(Other definitions for vertex that I've seen before include "Corner (of triangle)" , "Highest point" , "where sides meet" , "Summit" , "Crown, apex" .)