Tips in service of public house - The Front Line? (6)
I believe the answer is:
isobar
'front line?' is the definition.
(I've seen this in another clue)
'tips in service of public house' is the wordplay.
'tips' says to take the initial letters (I've seen 'tip of' mean this).
'public house' becomes 'bar' (I've seen this before).
The initial letters of 'in service of' is 'iso'.
'iso'+'bar'='ISOBAR'
'the' is the link.
(Other definitions for isobar that I've seen before include "Map line showing atmosphere pressure" , "Contour" , "As brio (anag)" , "Line on map connecting places of equal atmospheric pressure" , "It appears on some maps" .)