Be first in the field at Land's End (4)
I believe the answer is:
lead
'be first' is the definition.
(thesaurus)
'field at land's end' is the wordplay.
'field' becomes 'lea' (I've seen this before).
'at' means one lot of letters go next to another.
'end' suggests the final letters.
The last letter of 'land' is 'd'.
'lea'+'d'='LEAD'
'in the' is the link.
(Other definitions for lead that I've seen before include "Soft, heavy metal" , "initiative" , "chain" , "Church windows include this" , "Guide by going in front" .)