Ghastly male about to grab a taxi (7)
I believe the answer is:
macabre
'ghastly' is the definition.
(I know that ghastly can be written as macabre)
'male about to grab a taxi' is the wordplay.
'male' becomes 'm' (common abbreviation).
'about' becomes 're' (regarding).
'to grab' is an insertion indicator.
'taxi' becomes 'cab' (synonyms).
'm'+'re'='mre'
'a'+'cab'='acab'
'mre' enclosing 'acab' is 'MACABRE'.
(Other definitions for macabre that I've seen before include "'Grim, repellent (7)'" , "gruesome result" , "Ghostly appearance" , "Morbidly repellent" , "Gruesome and weird" .)