Lacking a cryptic clue for “tiny” (9)
I believe the answer is:
minuscule
'tiny' is the definition.
(thesaurus)
'lacking a cryptic clue' is the wordplay.
'lacking' becomes 'minus' (I've seen this before).
'a cryptic' indicates anagramming the letters (I've seen this in other clues).
'clue' is an anagram of 'cule'.
'minus'+'cule'='MINUSCULE'
'for' acts as a link.
(Other definitions for minuscule that I've seen before include "not capital" , "Fine" , "A lower-case letter" , "Not important" , "unimportant" .)