I appreciate that time is short for director (4)
I believe the answer is:
tati
'for director' is the definition.
(actor and director Jacques Tati)
'i appreciate that time is short' is the wordplay.
'i appreciate that' becomes 'ta' (informal way of saying thank you).
'short' indicates taking the first letters.
The first letters of 'time is' is 'ti'.
'ta'+'ti'='TATI'
(Other definitions for tati that I've seen before include "Creator of Monsieur Hulot" , "Jacques ----, French filmmaker" , "Jacques ___ , French comic actor and film director, d. 1982" , "Jacques -- (Monsieur Hulot's Holiday)" , "Jacques -, Fr. comedian" .)