Dash to capture crippled flotillas, essentially, in battle (2,7)
I believe the answer is:
el alamein
'battle' is the definition.
(Second World War battle)
'dash to capture crippled flotillas essentially' is the wordplay.
'dash' becomes 'elan' (synonyms).
'to capture' indicates putting letters inside.
'crippled' becomes 'lame' (synonyms).
'essentially' means to look at the middle letters.
The centre of 'flotillas' is 'i'.
'lame'+'i'='lamei'
'elan' enclosing 'lamei' is 'EL ALAMEIN'.
'in' acts as a link.
(Other definitions for el alamein that I've seen before include "victory" , "WWII battle" , "Place in Egypt where Montgomery defeated Rommel" , "North African WW2 battle site" , "North African World War two battle" .)