Work the lats! Yeah, diet, eat clean, do cardio.....but what then, so you strip down fat but if you have not worked on the frame of your build, once the fat melts off you are left with whatever shape is under there.
Pullups, assisted, spotted or horizontal area great stimulator for this, wide grip overhand.
Lat pulls are great but not as heavy as working with body weight.
Use some wide grips on your various row exercise options and don't forget that the rotator cuff under those shoulder blades need work too to help condition the area to take a higher load and volume.
Rhomboids also work with those rotators so some reverse pec dec work, reverse flies also work well to help hand it hand with the lat building.
Shoulders take a lot of strain with wide grip back work so conditioning those postural muscles of the rotator cuff and rhomboids are crucial.